Messages in this thread | | | Subject | Re: [mm][RFC][PATCH 0/11] mm accessor updates. | From | Peter Zijlstra <> | Date | Thu, 17 Dec 2009 09:45:34 +0100 |
| |
On Thu, 2009-12-17 at 09:40 +0100, Andi Kleen wrote: > On Wed, Dec 16, 2009 at 11:57:04PM +0100, Peter Zijlstra wrote: > > On Wed, 2009-12-16 at 19:31 +0900, KAMEZAWA Hiroyuki wrote: > > > > > The problem of range locking is more than mmap_sem, anyway. I don't think > > > it's possible easily. > > > > We already have a natural range lock in the form of the split pte lock. > > > > If we make the vma lookup speculative using RCU, we can use the pte lock > > One problem is here that mmap_sem currently contains sleeps > and RCU doesn't work for blocking operations until a custom > quiescent period is defined.
Right, so one thing we could do is always have preemptible rcu present in another RCU flavour, like
rcu_read_lock_sleep() rcu_read_unlock_sleep() call_rcu_sleep()
or whatever name that would be, and have PREEMPT_RCU=y only flip the regular rcu implementation between the sched/sleep one.
| |